ABSTRACT The world population is expected to rise by two billion in a few decades, boosting demand for soybean (Glycine max L.). Brazil has the world’s largest tropical agricultural area, accounting for 40 % of the world’s soybean output. This study was conducted to understand the potential and limitations of tropical soybean yield, estimate the amounts of main inputs (water and nutrients), and assess management to reach the crop yield potential (YP). We used CROPGRO-Soybean model, based on well-conducted experiments in different locations in Brazil. We generated estimates of YP and water-limited crop yield potential (YP-W), and explored long-term scenarios to evaluate the impact of sustainable practices on water management. Yield gap (YG) and agricultural efficiency (EA) were computed based on simulations and actual yield. The total water and nutrients required to achieve the YP in Brazil were also calculated. According to our simulations, YP ranged from 3,952 to 6,084 kg ha–1; YP-W from 3,133 to 5,186 kg ha–1, and YG from 589 to 4,401 kg ha–1. On average, drought stress negatively affected 14 % of YP, while 42 % of YP was lost due to management failures. Irrigation was needed in 26 % of the soybean-planted areas in Brazil to mitigate the risks associated to seasonal rainfall variations. Our findings revealed that it was possible to save around 20 % of the water through conservative soil practices and 25.0 106 Mg of macronutrients (N = 356 kg ha–1, P = 31 kg ha–1, K = 104 kg ha–1) annually is required to reach the exploitable soybean yield. decades Glycine L.. L L. . L.) worlds s area 4 output nutrients, , nutrients) YP. (YP) CROPGROSoybean CROPGRO Soybean model wellconducted well waterlimited limited YPW, YPW W (YP-W) longterm long term (YG EA (EA calculated 3952 3 952 3,95 6084 6 084 6,08 ha–1 ha1 ha 1 3133 133 3,13 5186 5 186 5,18 58 4401 401 4,40 average failures 2 soybeanplanted planted variations 250 25 0 25. 10 N 35 (YP (YP-W 395 95 3,9 608 08 6,0 ha– 313 13 3,1 518 18 5,1 440 4,4 39 9 3, 60 6, 51 5, 44 4,

ABSTRACT: Microbial biodiversity of an environment can contribute to plant growth and increase crop yield. Plant extracts from soybean (Glycine max (L.) Merrill) were investigated on soybean plants grown after inoculation with these extracts. Soil samples were collected from two important Brazilian soybean-growing regions to produce the extracts used in the experiments. The extracts were produced with material collected from aboveground biomass and rhizosphere of soybean plants cultivated in a controlled greenhouse (phase 1). The extracts produced in phase 1 were applied in a sequential experiment (phase 2). Phase 2 was conducted to examine the plant microbiome after the microbial alteration process in the greenhouse through seed inoculation with the extracts produced previously. Samples of aboveground biomass were collected to determine root dry matter and crop yield. Bacterial 16S rRNA sequences were processed to determine the final microbial content of soybean. The inoculated treatments had lower species diversity; however, the phyla Firmicutes and Bacteroidetes were more abundant in the treatments than in the non-inoculated treatment. The soybean plant stem in the inoculated treatment also had a positive response to enrichment of the bacterial classes Betaproteobacteria, Bacilli and Flavobacteria. Inoculation affected the microbial composition of soybean plants. The alteration of microbiome changes revealed differences for crop yield between the inoculated and non-inoculated treatments, with up to 93.5 % higher crop yields per plant according to the extract applied.